Is she a strong cyclist?

I'm skeptical.

What exactly did she discover. Meaning how did she quantify it?

My guess is rotor drag. I've picked it up several times when aero testing people. Even a slight rub can be as much as 4-6w drag. it can also negate any advantage a disc wheel may have. Now if you have rotor rub on your deep back wheel as well, I'd take the disc with rub over the deep dish with rub assuming the rubs are the same.

How does one quantify that? That's the rub.

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Brian Stover USAT LII
Accelerate3 Coaching
Insta

My rule of thumb is to always use my disc wheel. ALWAYS.

RP

I want to know the elevation of that course and tires on the disc and regular wheel. I’m a wheel whore and have tried so many different combinations to figure out the fastest setup. Disc is faster but if the course is hilly, yes it’s hard to spin the disc wheel climbing up.

As mentioned, the disc could have been rubbing. Some discs have more lateral flex than other wheels and can have some brake rub at the rim if the pads aren't centered and while cranking out of the saddle (very hard to generate this while seated though).

There is also the possibility that she just had a good day on the bike, nothing to do with wheel choice (correlation, not causation).

Discs are faster, period (unless you are doing the Alpe d'Huez triathlon). It's kinda their whole reason for existing. Of particular note is that there is not a minimum speed you need to ride at for a disc to be faster, so it's not like only pros and FOP AGs will see a benefit. Slower riders will actually save more time with a disc than faster ones (they get a smaller % gain, but are on course longer).

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ECMGN Therapy Silicon Valley:
Depression, Neurocognitive problems, Dementias (Testing and Evaluation), Trauma and PTSD, Traumatic Brain Injury (TBI)

On top of what has already been said on this thread, rear derailleur rub is also something that can happen if it's a course with steep inclines.

 Thanks for all the replies, rim brake, flat tt course. Time for a couple of test rides! Thanks again!

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 Thanks for all the input! Flat TT course, rim brake. Time for a few test rides! I use 25mm Zipp Tangente w/ latex tubes at 90-100 psi.

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Very likely way too much pressure.

90-100 is way too much. Try 60-80(?) depending on your weight.

Agree with above...

https://silca.cc/pages/sppc-form

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Kiwami Racing Team

She has no idea what she is talking about.

If I ran 60 to 80 psi I'd be pinch flatting on 25s all day, that's way too low. Even Silca recommends 91 psi for someone 160lbs

Maybe on 28s or 30s but not on 25s

Remember most disc wheels have a fairly narrow internal width. On my disc a 25mm tire measures 26 or 27mm, which at my weight means I'm also running around 90psi

That depends on how wide a 25mm Tangente is on that particular wheel. On my wheels (various FLO and HED), 25mm tires typically measure out to 28-29mm. So with a typical "25mm" tire, Silca recommends that I run 76-80psi (and I'm pretty sure I'm a lot heavier than you)...

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"I'm thinking of a number between 1 and 10, and I don't know why!"

"Opinions?"
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All things being equal, I don't think this is an opinion. The odds say a huge percentage chance the disc is faster, unless it is an all uphill time trial (not found in triathlon). Hard to believe she was faster on the spare wheel, again, all things being equal.

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David
* Ironman for Life! (Blog) * IM Everyday Hero Video * Daggett Shuler Law *
Disclaimer: I have personal and professional relationships with many athletes, vendors, and organizations in the triathlon world.

Agreed...my opinion is that all things were not equal in her testing and set-up and/or her testing was biased against the disk wheel set-up.

202 lbs plus bike

85 psi on 23 GP conti 5000 with latex tube

HED disc is max pressure 75 psi

Silca’s calculator is out of date

I must have some terrible roads, when I tried that I flatted all of the time. I never went through so many CO2 cartridges in a season :(

I'm probably not going to be able to articulate this very well, but you have to know how to ride fast and be aero and take advantage of the various equipment you have. I think some people will ride the same speed no matter what bike/wheels/setup they have. I've seen plenty of people get in to the sport, buy a budget bike, then eventually spend $10k on something decent and never get any faster.

Every single time I have experienced someone claiming this and had it turn out to be true it has wound up being either a malfunctioning hub or really bad tires on the disc. The classic example is, of course, disc wheel with Gatorskins vs training wheel with almost literally anything else.

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Tech writer/support on this here site. FIST school instructor and certified bike fitter. Formerly at Diamondback Bikes, LeMond Fitness, FSA, TiCycles, etc.
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I don't know what you're getting at and maybe this is directed at someone else but:

Does riding a 40K in just under an hour on 205 watts considered to be fast and aero? Or riding 20K in 28 min?

How about riding low 2:20's on a HIM on 165 to 175 watts? Then having a good run afterwards.

How about riding the the Scratch race, Points race, Keirin, Elimination and Madison at the track?
How about riding the Flying 200, 500, Kilo, 2K, 3K, and Team pursuit?

I'm pretty sure I'm done my share of fast riding.

That is fantastic

Do you do aero testing ?

Does that speed come out to what sun .17xxx?

It's more like .185 to .190, I'm very small so it's not hard to get that low for someone like me. I have been down as low as .168 but that wasn't sustainable for any length of time. It was very uncomfortable and I was unwilling to continue that route because I couldn't produce the power needed to consistently ride 30-32 mph.

Yes, I do my own aero testing. I do most of it on the track and verify on the road.

Super impressive

Flat out and back I did 235 watts avg 239 np 56 miles only averaged 24.04 MPH

I definitely need to do some testing

You're probably bigger than I am. At my best, my FTP was 235 watts at 62 Kg

Yes I am but that cda for that ride is approx .27xxx.


Have to be able to do better than that

24 mph at 235 watts is bad